Long-shaft stud driver



Jan.v 27;

K. B. GEERTSEMA LONG-SHAFT STUD DRIVER Filed Jan. 25, 1945 2Sheets-Sheet 1 KENNETH l.si GEERTSEMA INVENTOR.

BY IMT/amm ATTORNEY.

Jan. 27, 1948. K, B, GEERTSEMA 2,435,137l

LONG- SHAFT STUD DRIVER Filed Jan. 25, 1945 2 Sheets-Sheet 2 lazf"/mn/ENTR. KENNETH B. GEERTSEMA BY/msm 'ATTORNEY- Patented Jan. Z7, 1948:Kenneth rB. Geertsema, Valle to. Aircraft Screw Inc., Long Island City,N.

signor New York yStream, N. Y.as, Products Company, Yf, .arcdrlmra,ticolilwdf Application, January 25, 1945 Serial N` 574495 (ci..S11-1,13.)

AC laig'nns.

The invention relates to. a studdriver, vand more in particular to adriver` for long-shafted studs. .Studs Ioflthe kind hereunderconsideration haverin general, both end portions threaded, the` one to,be screwed Iinto a .boss andthe other oneforthe lengagement orly..threaded rlflerlflher` boss. For shortnessy` in thedescription-hereinafter and in the claims,A the .first mentionedendportion l will Lhe referred to as the lowerlthread or.bpsrsgengaging.portion-of thestud, and the other end portion as the`upper thread or nutengagingportion. Stud drivers of a, conventionaltype,va s, e. g., disclQSed in EU.v S. PatentNo. 2,334,988, -arg-1provided with :interiorlythreaded jaws` to. grip. the `upperAthreadrorton of. the stud'. and the ericht .thejawsis tightened when,owingto theendlof that portion engaging an abutment. ofuthe tool,anaxial force isset up betweenthe threadingscf the jaws and thegrippediportionunder the action of a torque appliedtodrive the stud homeinthe boss. Such a tool .operates-satisfactori1y if lapplied to a shortstud,k If,;ho,weyer, thestud has a relatively long shaft portionbetween,the Tupper and lower thread portionsthe lconventional toolis`objectionable because the total torque v required to s screw. thestudinto the bossmust be transmitted through therlength.ofv theshaftfrom the upper to the lowerportiono .the\.stud.,v Particularly,- if theshaft Mis relativelyslimand dimensioned Vto withstand merely or at leastmainly the occurring axial forces ofnormal use, the lmentioned torquemay dangerously overstress the stud shaft.y Further, the .conventionaldriver type. may. be Iobjectionable in .certain instances owing tothefact-that `itsubjects the threading oi the vnutfengaging portion not.vonly to. the ordinary Ystresses of a screw connectionbut-simultaneouslyto the very` appreciable radial compression of the grip. of the jaws.Itmayehappen, therefore, that the threading of-the .upper end of thestudbecomes deformed under .the applif yto be secured to such cationofthedriver-so much ,so-that thenut fitfor ywhiclrthe threading was cut willbeimpaired.

The invention aims .to provide a stud ,driver which isliree-oi the.criticized drawbacks ofthe conventional-type, and ,it consists mainlyin .the combination of means..wherein the grip of the. jaws. occurs. ata ystud portion vother f than the nutgengagingportion andclose -to thebosseen-r edging`A portion @While the vaxial `forces to tighten thejawAgrip act-l o r reaction thev end ofthe nutengaging-portion ofthe studbearing.; against Y an` abutment. o` the tool.

of the mentioned .Y

of a v-nut or other interi- The invention also sage through @themprovidesthefcombmetidh and of aportionbetween'vthat-upperthread opftionand the boss-*engaging portionfwith-:rr ILS toy close Athe jaws to;

determined-partida ,ofthe Stud )Shaft can engag? thetjaws Yor .the vjawslcan engage such; Afporti and with other vmeans, I1n.rightattile.3 grip;omni; jawswhen such-,engagement has occurred;

Further Objectspand: details of; thefirfw will be-apparentirom-thedescript matter and; the accompanying dra ing two embodiments;

11h the drawina Eig.1isa driver according to tool to a stud;

a position oi fEigs. 3 and 4 l are longitudinal c crossfsectipnflo-,WSWS?- themventdnfand n a csi-1 tion Toi the- Jaws prior Vtoheappldatieldf the cross-Sectionsfal isapartial side view-sofapartTthereofrl;v n d Eier dis-a 4cross-,se@tion da of the invention.;

other emhcdiment Reierrineinew tothe ',drawinetiies.; ;.tor=;4, f,thehan f illustratedstud-drivercomprisesa driving s 11e-.may besan liedhet, hewn An .elongated .Outer shell; .6 .errefnrlpaasea:ik 'tupper"portionL the :shank he ad .-2 and 1s-v in itawall, With-two eachotherthrough a tdllyn. a @plane 'rghtaneles t0 thermal-axiale as clearlyshown n--Eig. l Y

the bore,3..offthe.shank an a .set .screwin jects with .,itszends vinto,the slots 1 sot ,21S to the shankv and shell fromaxial Afpinriseseeilredbr mOi/@mentadativeiy tod eaen otrnerjbnt4 to4 permiterelativevrpta tionthrough an areR the slots 1. The

anchored of that headand vthe so vwoundiasto yoffer the shanklrelatively shellis shoulder IB at' a distan 2 Aand a torsion -springVaccordiueto .thdlengtht provided with arl, inner, 4cenelow 'theshanlthead I l Lislocatedioeftyveeh and i with its ends l zand Sie tothelower-.face

`shoulder I 0. -Thespring.is

-a .resistance :to I afrotation of;` to .the shellfinftherdirection othe: threading of gafstudufor, which theetoolls destinedt The: lower;

- 36 of a plunger-like pin as it will be described hereinafter. Thelower end of shell I1 is provided with as many longitudinal recesses25as there are jaws I E, i. e., three in the illustrated embodiment. Eachjaw has a shaft 26 engaging one of the recesses 25 hinged to the recesswall by means of a pivot pin 21, so that the jaws can open and close.Resilient means, such as springs 28 between each jaw and the inner shelltend to hold the jaws open or expanded -as far as the engaging faces I4and I 5 will permit. On the other hand, the jaws will be end of theinner shell I1 has an outer diameter notvlarger than the inner diameterof the cavity 4 ofthe shank head 2.

of bore 33, and with its y or shorter extension 33 the tool may be usedfor studs of various lengths.

` The stud driver just described is intended to be applied to a studsubstantially of a form indicated duced diameter extending downward fromthat portion 4I, a lower thread or boss-engaging portion 43,-and,intermediate the latter and the shaft, a portion 44 which is threaded sothat its threading may constitute a continuation of that of theboss-engaging portion. According to such a stud, the jaws I6 of thedriver are provided with an inner threading 39 to fit the stud portion44, and the pin 31 is so selected that in the position of Fig. 1 portion44 of a stud inserted into the shell bore' 24 is just below the jawswhen the upper end of the stud abuts against the lower end of the pinextension 38. For studs with shorter shafts, a pin of Van raccordinglylonger extension 38 is to the inner and outer shell be 4 be used, and apin of shorter extension is to be applied when the stud is longer.

Before the tool is applied to a stud, all parts are in the positionillustrated in the incline of the faces I4 and I5 are not strong enoughto out-balance the I1.) In this upper end of the stud engages the pin 31and lowering of the tool is continued screw 30 with the pin 31 and theinner shell I1 with the jaws I 5 are lifted in relation to the outershell 6. In order to make this movement this instance, the jaws owing tothe cooperation of the faces I4 and I5 are so far closed that the Jawthreading can be engaged by the threads of If now, the shank l is turnedpins 32 enter the cross-arm 5' of the L-slots 5 thereby locking thescrew and outer shell against relative axial movement. Bearing againstthe ends of these arms the pins take the screw 30 and inner shell I1along. Should the friction between greater than between the threading ofthe jaws, it may happen that the pins enter the slot portions 5' at alater time as will be described hereinafter. This, however, isimmaterial as to the functioning of the tool. Owing to the turning ofshell I 1 the jaws are screwed on stud portion 44 with the effect thatthe upper end of the stud pushes pin 31 upward within screw 30 againstthe restraint of spring 34. When stud portion 44 is screwed entirelyinto the jaws, pin 31 bears against the rubber member 34'. This is theposition of Fig. 2, and it is to be noted that still there is notightening of the jaws about the mit, whereupon the outer shell 6 willalso be taken along. The screw thread connection between screw 3U andthe inner shell Il will then cause an upward shift of the latter inrelation to the outer shell with the result that the grip of the jaws istightened on the stud owing to the cooperation of the inclined faces I4and I5. As soon as this grip is', tiene. ensue/h .to-overgametheliriction between Ss-.eneaeinefoortlon of :the/stud and 4the tappehole., the-torque,.appliedwlll tirato@ nd. .stud

scr-e. betweeothe .screw A30. andthe inner Shell.' 10aa-ira an axialforcecornponent will be set uplowing t-o.l the. thradinez s0 that areaction-might take. olaoerom! th'. t. .termina-three shell r11..-.tlf1tscr' w @n.notionot vthe jawsfand he s tud, t1aenupwards through the studand pin.31;,. .transr-nitted` to'. the bottom-0f the screw su andthlueh. the latterbaoK-tc the threading .29.. The stress thus occurringwhere the.

jaws engage the' Studfrprfv tion M'may have the effect that the threadsci` the stud -are stripped. This can be avoided .by the provision oi thecushion 34 and thecross-farms. I t has been stated that in thepositionof Fig. 2 the pins 32 are located -n .the crossfarms 5. In consequence,the pins, can bear on the lowerface 5"' indicated in Fig. 2a, whereasthe stud 4.0 and' pin 31 can still move slightly upwards in relation tothe screw 3|) according to the resiliency ofthe rubber 3,4'.Considering, now, the flux` of the axial force occurringy when shelll I1is lifted in relation to screw 30, and originating in. the. threading29, the path ci that. force Willbe. again through shell |1 and vjaws l5.Since, however, there iS. .not sufficient resistance to an upwardmovement of pink 31 owing to the cushion 34 the force or at least. anappreciable portion of it will be transmitted from the jaws to the outershell and from there through pin il .andshank l which with the faces 5"of the L-slots supports the pins 32,. Pins 32 nnally complete the pathof the forces. backto the screw 3l). Hence the provision of the cushion.3.4.' and thecroSS-arms 5' are .useful .to relieve the stud threading`from excessive stresses..y

When. the `tool is to be detachedirom the in. serted. stud a torque. inthe *opposite direction under the assistance rolftprirle H will tirst.return shellv l1 and the jaws. .to the position of Fig. 2.A whereuponthe, tool can be .readily ...screwed off the Blind.

Fromthe Yforegoing it `will be clear thatthe tool just described isuseful to drivelong'hafnted studs, andthatit is. applicable even-if alportion ofthe shaft or the nut engagingportion has a. diameter largerthan .the opening ofthe jaws in their position before vtheir lgrip istightened, :and: further that the tool is operative without-.subjectingthev studshait .to the stresses ci the ,drivits; torque andWithoutvendaneetinethe: threads. of the boss-engagingportionwandoiI-`the nut-enfk gaging portionfbyVV the clampingaction'othe, jaws.

In certain instances-...it is, undesirable, hat 1a portion `of the studIin/continuation yofgfgthe .bosse engaging portionis provided withathreadhe suchas the portion 44; .in Fig. L Inj such, a case the jaws,rather than-being interiorly threaded, may have any inner suitably.shapedA siplrfaace, Ypref-A erably rougher-led, e. g., knurled, toinctease the friction between the jaws and; theV stud. Hovv.. even-inthis connection, i-t .is to be noted that operation ofthe toclrednires.an axialY force being set upbetweenthelstud .and certain partsy ot thetool. In. theemtodimeptot Bies... 1; mathe. actionto.,suchte-riccamente- .ir1;.the. threading@ formed lin 4men'iber the 1rgnenfttmeaee. jaws .are-usada that.. tire tool. must, y be l pressedv`down upon d @that fa .reaction wouldoccur between the thradingof the`boss and thetbossfengaeing.

pQrtion of Ythe stud.l As inthe beginning yof the.

drivngoperation the stud will engage the boss wiitlflV only la verySmall portion of :the threading;

afg., onlyone 'or two thread oonvolutiona Vthe threading .may be.overstressed by the :axial-pres. Sure.of-..theftool.= This oanbeiavoidedifthe inner ehollpll'prcper :is :provided with an inner V,thread-t nogkto be engaged-hyv another .threading -of thgel Stud .shaft or-bythenut-engag-ing portion of .fthe

stud. -Suchafstructure 'is illustrated in the modi` cation .of 5.;

Thetool vaccording to Fig. 5 comprisesthe shank .it .with-head |02 whichts into the vcav-- ity lr03-.cita cup-shaped member` |04. From thebottom t'of the cavity downwardmember |504.

is provided with -an-lnter-ior -threading tllfinto which., anexteriorl-ythreaded extension |01tof.- the shank headi'xengages. A pin|08;sirnilar to..the..pin fl'in Fig-s. 1 andf, is secured to'lthe head:|02 andl .its v ends project into slots |09 '|614 similar-ly to theslots 1 of Fig.` 3.: "Howeverpslots 1&9 are :wider than :the pin'.lfflSitoiallowrf'orallimited relative axial movementoimember IM, whenthe head |02 is screwed infor out .of :the threading |06 according Ytothe..

length of the arcs of the slots |09.. It will'fbeclear that the-.pin IBB:will be. inserted andfsecured -ito the. head =|d2 only :attent-he.latter withitsexten.

sioriilf fhasibeen originally screwed down 1in-the VThe shank head H12vand mem-.- ber. |1541: are further ,connected to each other byl. and;

position ofy i-Fig. 5.

atonsi-on spring .l'til located inthe cavity anchored withy its ends HIand |12 in the nnen-I tioned parts respectively. Attachedbyscrews |113tothe member. 10.4.2is at its lower end lis interiorly flared at H5 Asoas totaper towards thel outside. The outershell lllt" is furtherprovided with a longitudinal recess ineits side wall to receive thereina key |`|1 se-v cured ,to the-stud-engaging member which includestheinner shell H8, an upper part-*H9 and the jaws |20. an interiorthreading |2| mating the nut-engaginglth-read' cfaJ stud to which thetool is intendedv to--be appli-ed and Iis further provided with an innershoulder |22= on top of `the threading The portion H9 maybe madeintegral with 'the sleeve I2-|19 Iorconnected `thereto byv dogs |23;'or

otherfsuitable means' in ord-er rto exchange it for;

another-one with dilerent Ainner threadingY |21; sov asA to render thetool applicable for studs of various sizes.y lShell |8- hasl an innerbore 411M sufficiently wide to permit passage of the wi'dfest part ofthe upper shaft.

The lower end of lshell l' |13 is slitted so as t0 form theaforementionedv jaws, |21! and the` structure is such that the shafts|25 of the j aws tend to spring outward. The outward l"2-6- cooperatingwith the inclined face ||;5, 'of the outer shell. It is, of course,possible too to A,make

the jaws as separate pieces and connect them to the .inner shellin theman-ner shown in Fig.; l,

Apin- |21 witha-n upper flange |-2'8Vis inserted: int@ the upperportionof part ||^9 'so as to be. axially movable andy rotatable betweenthe Shank head extension |81 and shoulder |2-2.

When the toolvv isl rst lowered on a stud |301 in embodiment. of; theinvention,

:the outer shell IM whichI Part H9 is vprovided' withstud threading andof thestu'olL v Spleadnlg. 0f; .the jawsv ifs limited by their inclined1.1111361?` falce stud. The upper stud portion in fact if in theoriginal position the jaws were not aluntil the stud threading |3| isdirectly below the thread |2| of part H9. When now a torque is appliedto the shank |U| the tool with threading |2| will be screwed on the studwhich thus is axially advanced within the studreceiving parts until pin|21 is pushed upward against the shank head extension |01, and the shellH8 is so far lowered in relation to the outer shell H4 that the jaws |28close around the stud portion |32 directly above the boss-engagingthreading |33. It is of course necessary to preselect the dimensions ofthe tool so in relation to the stud that the jaws engage the desiredstud portion. It will be clear that the movement of the jaws while theyclose on stud portion |32 is a helical one in relation to the stud owingto the thread |2| However, while the jaws tighten their grip `on thestud no relative movement should occur between these parts, first inorder to avoid wear, and second because of the fact that friction atrest is higher than under motion. For this reason the torsion springconnection is provided between the shank and the outer shell. This hasthe following effect: When owing to the initial closing of the jaws acertain friction and thus resistance is set up the shells will stopturning about the stud and rotation of the shank in relation to member|04 will take place against the restraint of the torsion spring lll).Owing to the engagement of the shank head with the threading |06, member|04 and with it the outer shell H4 will be raised relatively to theshank ||J| and also relatively to the inner shell H8. In consequence,the inclined faces |5 will act on the outer surface of the jaws |26 totighten the grip of the latter. When under such relative rotation of theshank |0| spring I l 0 is suiliciently tensloned the grip on the studwill be such that any increase of the torque will drive the stud intothe tapped hole of the boss member.

Now it will be clear that owing to the particular operation of the tooland although the nut-engaging portion of the upper stud portion is inengagement with the threading |2I, no driving torque is transmittedthrough the shaft of the 1s subjected torque to the boss-engagingportion of the stud occurs in close proximity to the latter and at aportion of the stud which is not injuriously affected by the occurringstresses.

It will be apparent to those skilled in the art that many alterationsand modications of the structure shown and described may be made withoutdeparting from the essence and spirit of the invention which shall notbe limited but by the scopeof the appended claims.

I claim:

1. A stud driver comprising a. drivingshank, an elongated -outer shellmember connected coaxially to said shank for common rotation with alimited lost motion, an inner shell member axially movable butnonrota-table in relation to said outer shell and substantially withinthe latter, said inner shell including spreadable and contractible jawsat its end remote from said shank and being so shaped as to receive inits interior an elongated shaft ofa stud to jaws having cooperatingfacesto contract said jaws upon movement of the latter in an axialdipinaxially movable in the other end of said inner shell, a screw-threadedpart in connection with Vsaid shank for comm-on rotation and engaging athreading of one of said shell members, said part constituting anabutment for said pin, means to transform axial pressure exerted by saidstud when engaging said pin into a shifting movement of said inner shellin relation to said outer shell so as to cause contraction of said jawsto a position preparatory to gripping said stud, and a torsion springsecured with its ends to one of said shell members and said shankrespectively to restrain rotation of said shank relatively to saidshells through the angle of said limited lost motion. Y

2. A stud driver comprising a driving shank, an elongated outer shellmember connected coaxially to said shank for common rotation with alimited threaded portion of said stud.

4. A device as claimed in claim 2, the connection of said shank and saidouter shell comprising a removable and insertable member so as to permitadjustment of in relation to said outer shell.

5. A stud driver comprising a shank member, an outer shell-like member,said shank and said shell member including inter-engaging screwthreadedportions, detachable means in engagement with said members to limitrotation of the and also including an inner threading for engagement bya threading be set, said outer shell and said said screw-threaded partof a stud inserted into said inner shell from the side of the jaws, saidjaws and said outer shell including interengaging slanting faces,whereby said inner shell will be shifted axially to close said jawsabout a portion of said stud remote from said inner threading when saidstud is screwed into the latter so as to exert axial pressure on thethreaded shank portion, and the grip of the jaws will be tightened whensaid shank is turned in relation to said outer shell against therestraint of the said spring.

6. A stud driver comprising a shank with a hollow head, an outer shellmember encompassing said head with one of its ends, a means connectingsaid head to said shell so as to permit turning of the shank and shellrelatively to each other through a predetermined angle but to preventrelative movement in axial direction, an inner shell member axiallyshiftable but non-rotatable in relation to said outer shell member, saidinner shell member being adapted to receive therein the shaft of a studto be set and including jaws at one of its ends, said jaws havingslanting faces cooperative with other slanting faces of said outer shellmember, said inner shell member being provided with a rst interiorthreading at its other end, said jaws being provided with a secondinterior threading for engagement of a threading of said stud, a torsionspring secured with its ends to one of said shell members and said shankrespectively, a screw engaging said iirst inner shell threading andincluding a head engaging into said shank head and being secured theretofor common rotation but axially shiftable a predetermined distance inrelation thereto, a pin axially movable in a central bore of said screwso as toconstitute .an abutment for said stud when inserted in saidinner shell, and a compression spring between said pin and said screw. v

'7. A stud driver as claimed in claim 6, the dimensions of the partsbeing so selected that said screw is shiftable in relation to said shankh ead a distance equivalent to the movement of the jaws from a fullyopen position to a position for engagement of said stud substantiallywithout gripping force.

8. In a stud driver the combination of an inner shell, includinginteriorly threaded jaws to engage a stud threading, an outer shell inco-axial engagement therewith, said jaws and said outer shell havingco-operative slanting faces to close the jaws by a relative movement ofthe shells, a screw member engaging with its threading said inner shell,a torque-transmitting connection allowing for a limited relative axialmovement between said screw member, means including a resilient memberin connection with said screw and receptive of axial pressure exertedthereon by said stud when engaging the threading of said jaws uponapplication of said tool, and locking means in the connection of saidscrew and outer shell to prevent .axial movement of the one in relationto the other and operative when a relative axial movement ofpredetermined length has occurred.

9. A device as claimed in claim 8, said locking means of said screwmember and said outer shell member comprising an L-shaped slot of theone and a pin secured to the other one of said members and engaging saidslot.

10. A stud driver comprising in combination a shank member including athreaded end portion, an outer shell member having a threaded portionengaged by said end portion, an additional connection of said shank andsaid outer shell, said connection including a torsion spring and meansto limit a helical relative movement of the connected members, an innershell non-rotatable but axially movable a limited distance within theouter shell, the end of the inner shell, remote from said shank, formingjaws to grip a stud inserted into the inner shell, the jaws and theouter shell having co-operative slanting faces to close the jaws by anaxial shift of the one shell relatively to the other, the inner shell,near its other end, being interiorly threaded to receive therein thethreaded end of said stud, and means to transmit to said shank thereaction to axial press sure exerted by said stud on the threading ofsaid inner shell thereby to cause an axial shift of the shell membersrelatively to each other.

KENNETH B. GEERTSEMA.

REFERENCES CITED The following references are of record ln the le ofthis patent:

UNITED STATES PATENTS

